Method of bending pipe material

ABSTRACT

In a bending method of bending a pipe material of metal in pipe working, at first particles are fed into a flow passage of the pipe material, the particles being removable in a liquid phase. The pipe material with the particles is bent. The particles in an at least partially liquid phase are removed from the pipe material, to clean the flow passage. The particles are meltable, or soluble in dissolving liquid. Specifically, in the removing step, the dissolving liquid is supplied into the flow passage, the particles are dissolved in the dissolving liquid, and compressed air is blown in the flow passage to eject the fluid obtained by dissolving the particles in the dissolving liquid. The particles are granulated sugar, and the dissolving liquid is warmed water.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of bending pipe material. Moreparticularly, the present invention relates to a method of bending pipematerial in which an inner surface of a flow passage of the pipematerial can be free from wrinkles.

2. Description Related to the Prior Art

A pipe material of metal is bent in a coil shape, arch shape or the likeby bending operation in a working method, and is used for variouspurposes. An outer surface of the pipe material becomes deformed in aneccentric shape. On an inner surface of a flow passage of the pipematerial, wrinkles are likely to occur. To prevent deformation of thepipe material as viewed in the cross section due to the bendingoperation, various methods are known. In one method, sand is filled inthe flow passage of the pipe material, which is heated before bending.JP-A 58-009723 discloses a method in which gaseous nitrogen is filled inthe pipe material, which is heated before bending.

In the method of filling sand before bending, there is a problem indifficulty in removal of sand from the pipe material. Even removal ofsand is carried out after the bending operation, part of the sand islikely to remain in the pipe material. This is a problem particularlyserious for the pipe material with as small a diameter as 1-10 mm.

In JP-A 58-009723, the inner pressure of the pipe material may changeremarkably in the heating or bending operation owing to the use of thegaseous nitrogen or the like. However, nothing in the document suggestsobservation of changes in the inner pressure. Control of the innerpressure is too difficult and cannot be used, because of danger ofbreakage of the pipe material and possible problems inconsistent to thesafety in the bending.

SUMMARY OF THE INVENTION

In view of the foregoing problems, an object of the present invention isto provide a method of bending pipe material in which an inner surfaceof a flow passage of the pipe material can be free from wrinkles.

In order to achieve the above and other objects and advantages of thisinvention, a bending method of bending a pipe material of metal includesa step of loading particles into a flow passage of the pipe material,the particles being processable in a liquid phase. The pipe materialwith the particles is bent. The particles in an at least partiallyliquid phase are removed from the pipe material.

The particles are meltable with heat, or soluble in dissolving liquid.

The pipe material has first and second end openings. Furthermore, thereis a step of closing the first end opening of the pipe material beforethe loading step.

Furthermore, the second end opening is closed after the loading step.

Preferably, the pipe material has first and second end openings.Furthermore, the first and second end openings are closed before thebending step.

Furthermore, the first and second end openings are opened after thebending step.

In the removing step, the dissolving liquid is supplied into the flowpassage to dissolve the particles.

In the removing step, the dissolving liquid is supplied into the flowpassage, the particles are dissolved in the dissolving liquid, andcompressed air is blown in the flow passage to eject fluid obtained bydissolving the particles in the dissolving liquid.

Supply of the dissolving liquid and blow of the compressed air arecarried out alternately and repeatedly.

In the blow of the compressed air at a final time, the flow passage isdried.

The particles are granulated sugar or salt, and the dissolving liquid iswater or warmed water.

In the removing step, the particles are melted with heat.

In the removing step, the pipe material is heated, and compressed air isblown in the flow passage to eject the fluid obtained by melting theparticles.

Also, a bending system for bending a pipe material of metal is provided.A material dispenser loads particles into a flow passage of the pipematerial, the particles being removable in a liquid phase. A shapingmold bends the pipe material with the particles. An ejector removes theparticles in an at least partially liquid phase from the pipe material,to clean the flow passage.

The particles are meltable, or soluble in dissolving liquid.

Consequently, an inner surface of a flow passage of the pipe materialcan be free from wrinkles, because the pipe material is filled withparticles at least partially for the purpose of safety in bending.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will becomemore apparent from the following detailed description when read inconnection with the accompanying drawings, in which:

FIG. 1 is an explanatory view in section illustrating a step of fillinga pipe material with granulated sugar;

FIG. 2 is a flow chart illustrating a bending method;

FIG. 3 is an explanatory view in section illustrating the pipe materialand caps for closing its ends;

FIG. 4 is an explanatory view in section illustrating bending of thepipe material;

FIG. 5 is a horizontal section illustrating ejection of granulated sugarfrom the pipe material;

FIG. 6 is a horizontal section illustrating blow of compressed air intothe pipe material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE PRESENTINVENTION

In FIG. 1, a pipe material 10 to bend according to a working method ofthe invention is illustrated. A material of the pipe material 10 iscopper. The pipe material 10 has an inner diameter d1 of 2-3 mm, and anouter diameter d2 of 3-5 mm. A female thread 10 a is formed in an innersurface of each of the ends of the pipe material 10, and used forsecuring a cap which will be described later. Steps of the process ofbending the pipe material 10 are illustrated in the flow of FIG. 2.

If the pipe material 10 is bent simply with a shaping mold, a flowpassage 10 b or inner space in the pipe material 10 will be madenarrower by local collapse of the pipe material 10. In view of this,granulated sugar 11 is fed and filled in the flow passage 10 b of thepipe material 10 as particles.

Before filling the pipe material 10 with the granulated sugar 11, afirst end opening 10 c of the pipe material 10 is closed by a cap 14 inhelical engagement at the step st1. Then the granulated sugar 11 is fedby a sugar dispenser 20 or sugar charger through a second end opening 10d into the flow passage 10 b of the pipe material 10. At the first endopening 10 c, there is no clearance where air can escape because of thefirm closing. However, the granulated sugar 11 can be filled in the flowpassage 10 b without difficulty at the step st2, because particles ofthe granulated sugar 11 are very fine with the grain property, and arelow absorbent in relation to moisture. Note that the granulated sugar 11is contained in the flow passage 10 b nearly fully, but not packedtherein with high tightness. Each particle of the granulated sugar 11should be movable with degree of freedom so as to allow the bend of thepipe material 10 to be described later.

When the flow passage 10 b of the pipe material 10 is filled with thegranulated sugar 11, the cap 14 in FIG. 3 is engaged with the second endopening 10 d helically for closing at the step st3. Thus, the granulatedsugar 11 is kept enclosed between the end openings 10 c and 10 d in thecourse of bending the pipe material 10 to be described later.

In FIG. 4, a cylindrical shaping mold 15 as pipe bender for use in thebending step of the pipe material 10 is illustrated. The shaping mold 15is formed from metal, ceramics or other materials, and has highrigidity. The pipe material 10 is pushed in contact with the surface ofthe shaping mold 15, and bent in a coil shape at the step st4 by windingoperation. The granulated sugar 11 is contained in the flow passage 10 bof the pipe material 10 with suitable tightness, so that the pipematerial 10 can be bent without narrowing the flow passage 10 b. Nodeformation occurs in the shape of a cross section of the pipe material10. Note that the pipe material 10 can be warmed at a temperatureslightly short of melting the granulated sugar 11 in the bending step.This is effective in facilitating the bend of the pipe material 10.

After completion of the bending step for the pipe material 10, the caps14 are removed to open the end openings 10 c and 10 d at the step st5.Then in FIG. 5, a hose or conduit 16 as ejector is connected with thefirst end opening 10 c of the pipe material 10. Warm water 17 asdissolving liquid is poured into the flow passage 10 b of the pipematerial 10 with temperature of 40 deg. C. or so at the step st6.

Although soluble in the warm water 17, the granulated sugar 11 does notdissolve abruptly inside the pipe material 10. When the warm water 17starts being poured into the flow passage 10 b of the pipe material 10through the first end opening 10 c, part of the granulated sugar 11starts dissolving in the warm water 17 in the vicinity of the first endopening 10 c. The warm water 17 penetrates between the inner surface ofthe flow passage 10 b and peripheral part of the granulated sugar 11.The peripheral part of the granulated sugar 11 starts dissolving. Theremaining part of the granulated sugar 11 comes to have smaller frictionwith the inner surface of the flow passage 10 b. Thus pressure of thewarm water 17 ejects the granulated sugar 11 through the second endopening 10 d.

After the pipe material 10 is supplied with the warm water 17 for five(5) minutes as predetermined time, the supply of the warm water 17 isstopped. The hose 16 is detached from the first end opening 10 c of thepipe material 10. In FIG. 6, a second hose or conduit 18 as ejector isconnected with the first end opening 10 c of the pipe material 10.Compressed air 19 is blown into the flow passage 10 b of the pipematerial 10 at the step st7. The remainder of the granulated sugar 11and sugar solution in the warm water 17 are ejected from the flowpassage 10 b.

After the compressed air 19 flows continuously for three (3) minutes,the second hose or conduit 18 is removed from the first end opening 10 cof the pipe material 10. Then the hose or conduit 16 is connected withthe first end opening 10 c to pour the warm water 17 into the flowpassage 10 b at the step st6. At the lapse of predetermined time, supplyof the warm water 17 is stopped. The second hose 18 is connected inplace of the hose 16, to blow the compressed air 19 into the flowpassage 10 b of the pipe material 10 at the step st7. The remainder ofthe granulated sugar 11 in the flow passage 10 b and aqueous sugarsolution in the warm water 17 are removed completely from the flowpassage 10 b at the step st8.

Final flow of the compressed air 19 dries the flow passage 10 b at thestep st9. Thus, the sequence of bending the pipe material 10 iscompleted.

In the embodiment, the material of the pipe material 10 is copper.However, metals as material of the pipe material 10 may be aluminum,iron and other substances. The working method of the invention isadvantageous particularly for pipes with a small diameter. Although thepipe material 10 has an inner diameter d1 of 2-3 mm, and an outerdiameter d2 of 3-5 mm according to the embodiment, the size of the pipematerial is not limited.

In the above embodiment, the pipe material is bent in a coil shape.However, the pipe material can be bent in other shape, for example, inthe L shape.

In the above embodiment, the warm water 17 of 40 deg. C. is poured intothe flow passage 10 b of the pipe material 10. However, the temperatureof the water as dissolving liquid for the granulated sugar 11 is notlimited, and can be room temperature. For example, the water asdissolving liquid may be tap water, and underground water as industrialwater, particularly in the season of summer.

In the embodiment, the granulated sugar is used. However, particles ofother substances soluble in dissolving liquid can be used instead, forexample, salt. Also, particles removable in a liquid phase may beparticles soluble in oil, particles meltable with heat, and chemicallysoluble or chemically removable particles, in other words, particles ofheat and/or solvent-liquefiable material. An example of particlesmeltable with heat is a thermoplastic bead. In a manner similar to theabove embodiment, compressed air flows in the flow passage in the pipematerial after dissolving particles, so as to eject the remainder of theparticles and its solution in dissolving liquid. The use of thecompressed air is the same also for the particles soluble in oil,chemically soluble or chemically removable particles, and the like.

In the above embodiment, each of the caps 14 is secured with threads byhelical engagement. However, the caps 14 can have a tightly fittablestructure without threads. Furthermore, each one of the end openings ofthe pipe material may be hammered for closing by deformation with ahammer or other tool. After closing of the end opening of the pipematerial by hammering, the hammered end portion can be cut away beforeremoving the granulated sugar 11.

In the above embodiment, compressed air is blown into the flow passageof the pipe material to remove remaining warm water and dry the flowpassage. However, it is possible in the invention to dry the pipematerial with heat in a drying chamber, or dry the same with naturaldrying after removing the granulated sugar.

In the above embodiment, the water and air are supplied in the directionreverse to that of feeding of the granulated sugar 11. However, thewater can be supplied and compressed air can flow in the direction thesame as that of the feeding of the granulated sugar 11 by entry throughthe second end opening 10 d.

In the above embodiment, supply of the warm water and blow of thecompressed air is repeated for two times. However, the repetition ofsupply and blow of those may be three, four, five or more times. Also,supply and blow of those may be one time if all the warm water and thecompressed air is removed sufficiently. In the above embodiment, thetime of supply of the warm water is 5 minutes. The time of blow of thecompressed air is 3 minutes. However, the invention is not limited tothose values.

Although the present invention has been fully described by way of thepreferred embodiments thereof with reference to the accompanyingdrawings, various changes and modifications will be apparent to thosehaving skill in this field. Therefore, unless otherwise these changesand modifications depart from the scope of the present invention, theyshould be construed as included therein.

1. A bending method of bending a pipe material of metal, comprisingsteps of: loading particles into a flow passage of said pipe material,said particles being processable in a liquid phase; bending said pipematerial with said particles; and removing said particles in an at leastpartially liquid phase from said pipe material.
 2. A bending method asdefined in claim 1, wherein said particles are meltable with heat, orsoluble in dissolving liquid.
 3. A bending method as defined in claim 2,wherein said pipe material has first and second end openings; furthercomprising a step of closing said first end opening of said pipematerial before said loading step.
 4. A bending method as defined inclaim 3, further comprising a step of closing said second end openingafter said loading step.
 5. A bending method as defined in claim 2,wherein said pipe material has first and second end openings; furthercomprising a step of closing said first and second end openings aftersaid loading step.
 6. A bending method as defined in claim 5, furthercomprising a step of opening said first and second end openings aftersaid bending step.
 7. A bending method as defined in claim 2, wherein insaid removing step, said dissolving liquid is supplied into said flowpassage to dissolve said particles.
 8. A bending method as defined inclaim 7, wherein in said removing step, said dissolving liquid issupplied into said flow passage, and compressed air is blown in saidflow passage to eject fluid obtained by dissolving said particles insaid dissolving liquid.
 9. A bending method as defined in claim 8,wherein supply of said dissolving liquid and blow of said compressed airare carried out alternately and repeatedly.
 10. A bending method asdefined in claim 9, wherein said flow passage is dried with saidcompressed air after said fluid is ejected.
 11. A bending method asdefined in claim 2, wherein said particles are granulated sugar or salt,and said dissolving liquid is water or warmed water.
 12. A bendingmethod as defined in claim 2, wherein in said removing step, saidparticles are melted with heat by heating said pipe.
 13. A bendingmethod as defined in claim 12, wherein in said removing step, said pipematerial is heated, and compressed air is blown in said flow passage toeject said fluid obtained by melting said particles.